Getting started with WebGL

WebGL enables web content to use an API based on OpenGL ES 2.0 to perform 2D and 3D rendering in an HTML canvas in browsers that support it without the use of plug-ins. WebGL programs consist of control code written in JavaScript and shader code (GLSL) that is executed on a computer's Graphics Processing Unit (GPU). WebGL elements can be mixed with other HTML elements and composited with other parts of the page or page background.

This article will introduce you to the basics of using WebGL. It's assumed that you already have an understanding of the mathematics involved in 3D graphics, and this article doesn't pretend to try to teach you 3D graphics concepts itself.

The first thing we do here is obtain a reference to the canvas, assigning it to a variable named canvas.

Once we have the canvas, we try to get a WebGLRenderingContext for it by calling getContext and passing it the string "webgl". If the browser does not support webgl getContext will return null in which case we will display a message to the user and exit.

If the context is successfully initialized, the variable gl is our reference to it. In this case, we set the clear color to black, and clear the context to that color (redrawing the canvas with the background color).

At this point, you have enough code that the WebGL context should successfully initialize, and you should wind up with a big black, empty box, ready and waiting to receive content.

See also

An introduction to WebGL: Written by Luz Caballero, published at dev.opera.com. This article addresses that what WebGL is, explains how WebGL works (including the rendering pipeline concept), and introduces some WebGL libraries.

An intro to modern OpenGL: A series of nice articles about OpenGL written by Joe Groff, providing a clear introduction to OpenGL from its history to the important graphics pipeline concept, and also includes some examples to demonstrate how OpenGL works. If you have no idea what OpenGL is, this is a good place to start.